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Glossary of common biostatistical and epidemiological terms

Peter A L Bonis, MD
Section Editors
Joann G Elmore, MD, MPH
David M Rind, MD
Deputy Editor
Carrie Armsby, MD, MPH


This topic review will provide a catalog of common biostatistical and epidemiological terms encountered in the medical literature.


Measures of central tendency — Three measures of central tendency are most frequently used to describe data:

Mean equals the sum of observations divided by the number of observations.

Median equals the observation in the middle when all observations are ordered from smallest to largest; when there are an even number of observations the median is defined as the mean of the middle two data points.

Mode equals the observation that occurs most frequently.

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Literature review current through: Nov 2017. | This topic last updated: Feb 22, 2016.
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